Effect of G-CSF on Pulpal Inflammation in Rat

Objectives: The purpose of the present study was to examined the effect of granulocyte colony stimulating factor (G-CSF) on pulpal inflammation in rat. Methods: The pulpal inflammation was made by pulpal exposure in rat mandibular first molar. G-CSF were injected everyday in normal and neutropenic rat induced by Methotrexate (MTX) injection once a day for 3 days before the exposure. The pulpal tissue was histologically investigated at 2, 4, 7, and 10 days after the exposure. Moreover, rat peripheral blood neutrophils were collected to examine the neutrophil functions. The chemotaxis was evaluated using a 48-well modified Boyden chamber, and the phagocytosis was measured by flow cytometry. Results: In normal rat, necrosis and inflammation gradually enlarged in pulpal tissue. After G-CSF injection, the number of neutrophil in blood was increased, but did not change the pulpal inflammation. The chemotaxis and phagocytosis of neutrophil were greater than those of normal one. After MTX injection, the neutrophil count in blood was decreased, and the area of the pulpal necrosis was far greater as compared with that of normal one. The functions of neutrophil were weaker than those of normal one. When G-CSF were injected in neutropenic rat, the neutrophil count increased and the area of the pulpal necrosis was inhibited as compared with those of neutropenic one. The functions of neutrophil were recovered from neutropenia with MTX. These results were suggested that the neutrophil defended bacterial invasion in pulpal tissue. Conclusions: This study exhibited that G-CSF recovered the functions of neutrophil and inhibited the increase of the pulpal necrosis in neutropenic rat